1. Field of the Invention
The present invention relates to a recording apparatus. More particularly, the invention relates to an ink jet recording apparatus capable of reciprocating a carriage having a recording head mounted on it for scanning and recording; to a process to be executed when the ink remains in such a recording apparatus are reduced; and to a discharge recovery process for the recording head to be used by such an apparatus.
Also, the present invention relates to a power control method for a recording apparatus.
2. Related Background Art
In the so-called serial type recording apparatus which records by the reciprocation of a carriage having a recording head mounted on it for correlatively scanning a recording medium, there is a problem that the recording position is displaced due to the backlash of the driving system which takes place as the carriage reciprocates. In consideration of a backlash of the kind, it has been a practice to make a correction in order to provide a delayed timing for a recording operation of the recording head (hereinafter referred to as a "backlash correction"). The data for this backlash correction are set in a back up memory and others when the apparatus is assembled at a factory, for example. Then, some systems are made available after that in order to allow a user to modify the backlash data appropriately by use of dip switches and others.
However, it is extremely troublesome for the user to modify the backlash data by the switches and others for the adjustment of the required timing of a recording operation. Furthermore, it is difficult for the user to optimize such an adjustment.
As an apparatus for recording characters and images on a recording medium such as a sheet, there has been a recording technique on an impact type recording thereby to press an ink ribbon which retains ink to a recording medium for recording. In a recording apparatus using such a technique, a user recognizes the life of the ink ribbon when the density of a recorded image is reduced due to the lessened amount of ink retained in the ink ribbon after a number of recording sheets have been recorded.
On the other hand, in an ink jet recording apparatus which records characters and images on a recording medium such as a sheet by discharging fine ink droplets onto it, there are many advantages as follows as compared with the other recording apparatuses:
(1) A high-speed recording is possible. PA1 (2) The use of colors is easy. PA1 (3) An ordinary paper is usable for recording. PA1 (4) The noises are small. PA1 (5) The quality of the recorded images is excellent.
In an ink jet recording apparatus such as this, the structure is made by the provisions of a recording head which is generally used for recording, and an exchangeable ink cartridge which contains ink to be supplied to the recording head.
In the foregoing ink jet recording apparatus, too, the ink remains in the ink cartridge are reduced as a number of sheets are recorded, and then, it becomes impossible to record eventually due to the short supply of ink. Therefore, it is a general practice that the ink remains in the ink cartridge are always monitored, and when the content of ink becomes less than a specific amount, a lamp is illuminated or a message is displayed so that the user is informed of the insufficient ink remains.
Here, in the conventional ink jet recording apparatus, the ink remains in the ink cartridge are monitored, and the user is prompted to replace the ink cartridges or to procure a new cartridge when the ink remains become less than a specific amount. However, in such an ink jet recording apparatus, the recording is suddenly disabled when the ink remains become less than a threshold value set for the recordable amount of the ink remains. As a result, a problem tends to be encountered that the data still to be recorded lost or the medium still on recording is wasted.
Also, in general, an ink jet recording apparatus comprises a recording head on which a plurality of nozzles are provided in array with the ink discharging ports arranged at its leading ends at pitches of 1/180 inch, 1/240 inch, or the like. In such a recording head, the solvent of the recording liquid (hereinafter referred to as ink) at the discharging ports is evaporated when the head is out of recording, that is, on standby for recording, for example, hence making the ink over viscous, which may bring about the reduction of the amount of dischargeable ink, the deviation of the direction in which the ink is discharged, or some other defective discharges. Thus, the dot missing, the displacement of impacted positions of ink droplets on a recording medium, or other defects are invited to create a problem that the quality of the recorded image and others is spoiled.
This problem may also take place in the same manner at the time of a recording operation. In other words, when recording, the ink is selectively discharged from among a plurality of discharging ports to form an image. Therefore, in terms of the individual nozzles, there is a possibility that some of them remain in a state where its leading ends are exposed to the atmosphere as they are without being accompanied by any ink discharging. In such particular nozzles, therefore, the viscosity of ink is increased as described above.
For the problems such as these, a discharge recovery process has been taken as a countermeasure as described below. In other words, when the apparatus is out of recording operation, a cap which is usually made of a flexible rubber or the like abuts upon the surface where the discharging ports of the recording head are arranged (hereinafter referred to as discharge surface) in order to suppress the evaporation of the ink solvent from the discharging ports or to execute an ink discharging which is not related to recording in a given location for the purpose of removing the ink which has already become overly viscous (hereinafter referred to as preliminary discharge), hence preventing any defective discharge from occurring.
Further, for the recovery process for the nozzles which are not in use when recording, a technique is adopted so that the preliminary discharge is repeated at intervals of a specific period during the recording operation.
Also, for the purpose of removing the ink which has advanced the degree of its viscosity, the ink may be sucked from the discharging ports through the cap or a process may be given to pressurize the ink from the ink supply system for the recording head (hereinafter referred to as suction or pressurized recovery process accordingly).
However, there are still problems encountered in executing the conventional recovery processes in some cases.
In other words, the evaporation of the ink solvent from the discharging ports advances as the time elapses, and when starting a recording, the length of such an elapsed time differs greatly depending on the conditions in which the apparatus has been used until then. Therefore, the discharging number of the preliminary discharges must be set in preparation to cope with any the situation that may be brought about by the increased viscosity of ink which should become comparatively great after the evaporation has advanced and reached its saturation to a certain extent. The same is applicable to the preliminary discharge which will also be executed during the recording operation.
In this respect, when the cap abuts upon the discharge surface for the suppression of the evaporation, it may be difficult to anticipate completely preventing the ink solvent from being evaporated from the discharging ports. Therefore, in this case, too, the setting of the discharging number of the preliminary discharges should be considered in the same manner as above. Also, when the evaporation has further advanced, it may be necessary to apply the foregoing suction or pressurized recovery process, and in some cases, it is still conceivable that simply applying the preliminary discharges alone is not good enough, and a defective discharge may ensue.
Further, for the recovery process for the nozzles which are not in use during a recording operation, it is necessary to execute the preliminary discharge for covering the maximum increase of the viscosity rather than the frequency of use per nozzle in order to stabilize the discharging of all the nozzles. As a result, the probability is that the preliminary discharging may be executed in an amount which is more than necessary for some of the nozzles.
When the discharging number is set for the preliminary discharges such as above, there is also a case that the preliminary discharges are executed more than necessary depending on the condition of use of a recording apparatus: for example, its out-of-recording time is comparatively short or the discharging ports which execute a small number of discharges are scarcely present. Then, in such a case, the amount of used ink for the operation other than recording becomes great, inevitably leading to an increased running cost. Still more, in case of a cartridge type where a recording head and an ink tank are integrally formed, both the tank and recording head must be replaced when the ink is exhausted. This replacement of the cartridge affects the running cost, hence any unwanted use of the recording liquid should be suppressed as much as possible. The amount of ink to be used for the discharge recovery process such as the above-mentioned preliminary discharges must be reduced in attaining a more effective use of the ink retained in the ink tank.
Also, recently, among the note type personal computers, word processors, and the like, those having a printer integrally arranged for them have gained popularity. An equipment of the kind is driven by its built-in cell or the power supplied through an AC adapter in addition to the AC power-supply. Therefore, it is desirable to enable the printer used for such an equipment to be driven by a low power dissipation. Along the enhancement of the computer performance, a higher speed of a printer has also become one of the significant factors to determine the product value.
For a portable printer of the kind, a direct current voltage is supplied from an externally equipped AC adapter, or from cells and the like. This voltage is increased or decreased by a DC-DC converter, a regulator IC, or the like to generate the required direct current voltage in the apparatus. In order to increase the printing (or image printing) speed in this type of a printer, it is necessary to increase the frequency of the ink discharges if the printer is of an ink jet type. Also, in a case of a serial printer, the scanning speed of a head carriage must be increased.
However, as described earlier, if the printing speed of the printer should be increased, the power required to drive the ink jet head or the carriage motor is increased almost in proportion to the intended speed. Consequently, the size of the cells, the AC adapter or the like should become larger or the AC-DC converter should be made greater. This inevitably brings about a disadvantage that the cost will be increased significantly for such an equipment as a whole.